Previous studies have shown abnormal growth of fibroblasts in adult patients with diabetes mellitus. This grant is defining certain aspects of cell growth in children with juvenile onset diabetes mellitus. Particular emphasis is being placed on identification of the site of the cell cycle or a step of protein synthesis which is responsible for the slow cell growth. Cell synchronization with serum starvation and thymidine labeling is being used to measure G1 phase. Collagen mRNA levels, measured in a reticulocyte lysate, and collagen transit time are studied to ascess protein synthesis at the translational and transcriptional level. These studies may demonstrate if the growth abnormalities are an acquired or primary abnormality in diabetes. The same methods for assessing collagen mRNA levels and utilization are being used to define the mechanism of activity of insulin, PTH and 1,25 hydroxy Vitamin D on collagen synthesis in the fetal rat calvaria.